1. Field of the Invention
The invention relates to a method for finishing textile material containing synthetic fibers, especially a web of textile material with evaporable finishing means which form a solid solution with the material of the synthetic fibers, and in which the finishing means are evaporated and are transferred in the vaporous phase to the textile material by means of a carrier gas. The term "evaporable finishing means" is understood to mean in the present context processing agents, dyes, optical brighteners and similar treatment agents used in the textile industry for textile material in fiber, thread, sheet or web form. The term "textile material" refers primarily the above-mentioned categories.
2. Description of the Prior Art
In the journals "Journal of the Society of Dyers and Colourists", Vol. 82, September 1966, pages 333 to 338, as well as "Melliand Textilberichte", 1972, pages 1265 to 1270, and 1977, pages 844 to 850, a method is described, in which a pure dispersion dye which does not contain additives such as adulterants and dispersion agents, is heated, melted and evaporated as well as transferred in this state directly to a substrate. Since the speed with which the dye changes into the vapor phase, depends on the size of the dye particles and increases as the square with decreasing particle diameter, monomolecular dyes have a relatively high partial vapor pressure in the melted, liquid state.
If a textile material is to be finished by the known method, the vapor deposition would have to be followed by a treatment process, in which the vapor-deposited finishing agent diffuses into the individual textile fiber. Up to the completion of this treatment process proper, however, there is the danger of the substance applied to the textile material to smudge or blur, as in the conventional dye-fixing from the liquid phase. In vapor-depositing pure dye in a continuously operating treatment unit, the further disadvantage can be expected that in the time between the beginning and the end of the fixing operation following the vapor deposition, a considerable part of the just vapor-deposited material is not bound in contrast to the present dyeing process from the liquid phase as a result the vapor-deposited material, evaporates again from the substrate and is lost and even contaminates not only the parts of the machine which are to be kept clean but also the exhaust air.
In this category a method of the kind can be found in the older DE-OS No. 32 18 142. It is attempted with this method to make the intermediate carrier required in the transfer printing method described, for instance, in DE-OS No. 23 12 418, unnecessary. In transfer printing, the dye, with or without intermediate carrier, is transferred from the gaseous phase by resublimation to the textile material, paper or the like. If, for instance, dispersion dyes are to be applied to polyethylene fibers, a process step must again follow, in which the dye must be fixed on or in the fiber. In fixing, the dye is dissolved in the evaporated state in the respective synthetic fiber.
The finishing, and especially the dyeing of synthetic fibers, for instance, polyethylene fibers with dispersion dyes, also takes place in the so-called thermosol process, in which the dye is applied to the textile material in dissolved form. In this method, drying takes place first after the dissolved finishing agent is padded and then, the textile material is heated in a fixing stage to a high temperature and for a sufficient length of time to diffuse. the dye "in gaseous condition" into the individual textile fibers and form with the material of the fibers a so-called solid solution.
It is a disadvantage of the older methods that a separate process step requiring thermal energy is required for dissolving and fixing. However, it is even more disturbing in practice that up to the conclusion of the dissolving process the danger of smudging and blurring of the substance applied to the textile material exists in the modified transfer printing method (which does not require an intermediate carrier) as well as in the thermosol method.